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| author | Andreas Rheinhardt <andreas.rheinhardt@gmail.com> | 2019-11-17 08:34:36 +0100 |
|---|---|---|
| committer | James Almer <jamrial@gmail.com> | 2019-12-31 16:57:37 -0300 |
| commit | 4667920455c0d52c25835ff81098254213f2d018 (patch) | |
| tree | 431dbc0a0d8c4ecdf052e06cf25c8a50d03dd809 | |
| parent | 1cf238d3bfefdfd3345ca262f57e08a798bb0d90 (diff) | |
| download | ffmpeg-4667920455c0d52c25835ff81098254213f2d018.tar.gz | |
avcodec/cbs: Fix potential overflow
The number of bits in a PutBitContext must fit into an int, yet nothing
guaranteed the size argument cbs_write_unit_data() uses in init_put_bits()
to be in the range 0..INT_MAX / 8. This has been changed.
Furthermore, the check 8 * data_size > data_bit_start that there is
data beyond the initial padding when writing mpeg2 or H.264/5 slices
could also overflow, so divide it by 8 to get an equivalent check
without this problem.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
(cherry picked from commit cda3e8ca04c0e343f5b60fda8fb467936e176f33)
| -rw-r--r-- | libavcodec/cbs.c | 4 | ||||
| -rw-r--r-- | libavcodec/cbs_h2645.c | 2 | ||||
| -rw-r--r-- | libavcodec/cbs_mpeg2.c | 2 |
3 files changed, 5 insertions, 3 deletions
diff --git a/libavcodec/cbs.c b/libavcodec/cbs.c index 047f4fb898..0ce66170ec 100644 --- a/libavcodec/cbs.c +++ b/libavcodec/cbs.c @@ -309,7 +309,9 @@ static int cbs_write_unit_data(CodedBitstreamContext *ctx, if (ret < 0) { if (ret == AVERROR(ENOSPC)) { // Overflow. - ctx->write_buffer_size *= 2; + if (ctx->write_buffer_size == INT_MAX / 8) + return AVERROR(ENOMEM); + ctx->write_buffer_size = FFMIN(2 * ctx->write_buffer_size, INT_MAX / 8); goto reallocate_and_try_again; } // Write failed for some other reason. diff --git a/libavcodec/cbs_h2645.c b/libavcodec/cbs_h2645.c index ba442b62ed..e272b0bcf6 100644 --- a/libavcodec/cbs_h2645.c +++ b/libavcodec/cbs_h2645.c @@ -1101,7 +1101,7 @@ static int cbs_h2645_write_slice_data(CodedBitstreamContext *ctx, const uint8_t *pos = data + data_bit_start / 8; av_assert0(data_bit_start >= 0 && - 8 * data_size > data_bit_start); + data_size > data_bit_start / 8); if (data_size * 8 + 8 > put_bits_left(pbc)) return AVERROR(ENOSPC); diff --git a/libavcodec/cbs_mpeg2.c b/libavcodec/cbs_mpeg2.c index a49a403b26..98a22e3a68 100644 --- a/libavcodec/cbs_mpeg2.c +++ b/libavcodec/cbs_mpeg2.c @@ -301,7 +301,7 @@ static int cbs_mpeg2_write_slice(CodedBitstreamContext *ctx, uint8_t *pos = slice->data + slice->data_bit_start / 8; av_assert0(slice->data_bit_start >= 0 && - 8 * slice->data_size > slice->data_bit_start); + slice->data_size > slice->data_bit_start / 8); if (slice->data_size * 8 + 8 > put_bits_left(pbc)) return AVERROR(ENOSPC); |